Project Summary/Abstract The mechanisms by which RNA splicing is tightly coordinated with transcription to ensure accurate and efficient gene expression are not well understood. This gap in our knowledge represents a significant problem in understanding the molecular basis for how the misregulation of gene expression results in human disease, including neurological disorders and cancers. The applicant's long-term goal is to use the highly tractable yeast Saccharomyces cerevisiae as a model organism to investigate mechanisms that reciprocally couple transcription with RNA splicing. The central objective of this work is to investigate novel connections between RNA splicing and chromatin-modifying complexes, which modify histone proteins and remodel chromatin structure to regulate transcription. The central hypothesis is that histone acetylation by the NuA4 complex and H2A.Z deposition by the Swr1 complex stimulates RNA splicing, which in turn promotes NuA4 and Swr1 function to reciprocally couple transcription with RNA splicing. This hypothesis is based on the applicant's published and preliminary work, as well as reports in the literature. The rationale for the proposed research is that deciphering the mechanisms of reciprocal coupling between RNA splicing and chromatin modification/remodeling is a critical step in understanding the molecular basis of disease development and will lead to novel therapeutic targets. The central hypothesis will be tested by pursuing three independent but related specific aims: 1) To determine the mechanism by which NuA4 and Swr1 regulate RNA splicing; 2) To determine the extent to which RNA splicing can promote NuA4 and/or Swr1 activity or association with chromatin to modulate transcription; and 3) To identify additional chromatin modification/remodeling enzymes, histone modifications, or variant histones that can link RNA splicing with transcription. Genetic, biochemical and molecular biology approaches, which have been established as feasible in the applicant's hands, will be employed to accomplish these goals. The proposed work is innovative because it aims to test the novel hypothesis that RNA splicing is reciprocally coupled with transcription via chromatin modification and remodeling by NuA4 and Swr1. Additionally, the applicant will utilize established genetic approaches to complete an innovative genetic interaction study to identify additional chromatin modifying enzymes, specific histone modifications and/or variant histones that function in coupling transcription and RNA splicing. The contribution of the proposed research is expected to elucidate the mechanism by which NuA4 and Swr1 work with the splicing machinery to coordinate the reciprocal coupling of transcription and RNA splicing, as well as identify additional chromatin modification candidates that coordinate crosstalk between transcription and RNA splicing. The contribution of this research is significant because the identification of factors and specific mechanisms that mediate the coordination between transcription and RNA splicing provides a basis for the development of therapeutic agents to target mammalian homologs in order to prevent or treat human disease.